Randomized, double-blind, dose-ranging study of pentosan polysulfate sodium for interstitial cystitis

Nickel JC, Barkin J, Forrest J, Mosbaugh PG, Hernandez-Graulau J, Kaufman D, Lloyd K, Evans RJ, Parsons CL, Atkinson LE · Urology

Symptom scores improved on all three doses — mean O'Leary-Sant index from about 11.5 to about 8.3 — but tripling the dose changed nothing, with responder rates of 49.6%, 49.6% and 45.2% at 300, 600 and 900 mg. The authors concluded duration of therapy mattered more than dose.

Population

380 adults with interstitial cystitis, US multicentre, 32 weeks

Intervention

Oral PPS at 300, 600 or 900 mg daily

Comparator

The other two dose arms (no placebo arm)

Limitations

No placebo arm, so the within-arm improvement is not attributable to the drug; the flat dose-response is the interpretable finding, and it sits awkwardly beside a claim of pharmacological effect.